El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / This paper, evaluates a proposal for an external bend fluvial erosion control, using submerged vanes as velocity and shear stress control, verifying its effectiveness by modeling in Iber to calculate the scour produced by discharges with different return periods. The results indicate that the velocity, shear stress and scour decrease along the curve, due to submerged vanes.

This thesis focused on investigating flow, coherent structures, and mechanisms leading to scour around a series of three submerged groynes in a high curvature (radius of curvature (R)/channel width (B)=1.5) channel bend using a Large Eddy Simulation Numerical (LES) model. Flow was investigated during both an initial and a later stage of scour. The results showed that the groynes appeared effective in keeping the main core of high streamwise velocity away from the outer bank wall in the region where they were installed, although high potential still existed for local scour around the groynes. During the initial stage of scour, horseshoe vortices (HVs) showed the greatest propensity to induce scour immediately upstream of the groyne tips. During the later stage of scour, the HV in front of the first upstream groyne (G1) induced very high mean pressure fluctuations on the outer bank wall. Scour was also of very great concern around the tip of G1 due to severe mean bed pressure fluctuations. Downstream of the groyne field, the presence of a counter-rotating outer bank cell was capable of endangering the stability of the outer bank. The second focus of this thesis was to investigate flow in a 135° channel bend using both Reynolds Averaged Navier Stokes (RANS) and LES numerical models. The RANS study examined the effects of curvature ratio (R/B), and aspect ratio (B/H, where H is the inlet flow depth), on secondary circulation strength, and bed shear stresses. The study revealed that a decrease in R/B was associated with an increase in secondary circulation strength and peak bed shear stress. A change in B/H also substantially affected cross stream circulation strength. The LES study was conducted in a 135° (R/B = 1.5) bend flume with a fixed bed corresponding to near equilibrium scour conditions, and the results were compared to a similar high curvature 193° bend numerical study. Inner bank vortices and shear layers were present in both cases although their characteristics were substantially different. Distributions of boundary friction velocities, and turbulence were also quite different for each case.

This thesis focused on investigating flow, coherent structures, and mechanisms leading to scour around a series of three submerged groynes in a high curvature (radius of curvature (R)/channel width (B)=1.5) channel bend using a Large Eddy Simulation Numerical (LES) model. Flow was investigated during both an initial and a later stage of scour. The results showed that the groynes appeared effective in keeping the main core of high streamwise velocity away from the outer bank wall in the region where they were installed, although high potential still existed for local scour around the groynes. During the initial stage of scour, horseshoe vortices (HVs) showed the greatest propensity to induce scour immediately upstream of the groyne tips. During the later stage of scour, the HV in front of the first upstream groyne (G1) induced very high mean pressure fluctuations on the outer bank wall. Scour was also of very great concern around the tip of G1 due to severe mean bed pressure fluctuations. Downstream of the groyne field, the presence of a counter-rotating outer bank cell was capable of endangering the stability of the outer bank. The second focus of this thesis was to investigate flow in a 135° channel bend using both Reynolds Averaged Navier Stokes (RANS) and LES numerical models. The RANS study examined the effects of curvature ratio (R/B), and aspect ratio (B/H, where H is the inlet flow depth), on secondary circulation strength, and bed shear stresses. The study revealed that a decrease in R/B was associated with an increase in secondary circulation strength and peak bed shear stress. A change in B/H also substantially affected cross stream circulation strength. The LES study was conducted in a 135° (R/B = 1.5) bend flume with a fixed bed corresponding to near equilibrium scour conditions, and the results were compared to a similar high curvature 193° bend numerical study. Inner bank vortices and shear layers were present in both cases although their characteristics were substantially different. Distributions of boundary friction velocities, and turbulence were also quite different for each case.

This thesis focused on investigating flow, coherent structures, and mechanisms leading to scour around a series of three submerged groynes in a high curvature (radius of curvature (R)/channel width (B)=1.5) channel bend using a Large Eddy Simulation Numerical (LES) model. Flow was investigated during both an initial and a later stage of scour. The results showed that the groynes appeared effective in keeping the main core of high streamwise velocity away from the outer bank wall in the region where they were installed, although high potential still existed for local scour around the groynes. During the initial stage of scour, horseshoe vortices (HVs) showed the greatest propensity to induce scour immediately upstream of the groyne tips. During the later stage of scour, the HV in front of the first upstream groyne (G1) induced very high mean pressure fluctuations on the outer bank wall. Scour was also of very great concern around the tip of G1 due to severe mean bed pressure fluctuations. Downstream of the groyne field, the presence of a counter-rotating outer bank cell was capable of endangering the stability of the outer bank. The second focus of this thesis was to investigate flow in a 135° channel bend using both Reynolds Averaged Navier Stokes (RANS) and LES numerical models. The RANS study examined the effects of curvature ratio (R/B), and aspect ratio (B/H, where H is the inlet flow depth), on secondary circulation strength, and bed shear stresses. The study revealed that a decrease in R/B was associated with an increase in secondary circulation strength and peak bed shear stress. A change in B/H also substantially affected cross stream circulation strength. The LES study was conducted in a 135° (R/B = 1.5) bend flume with a fixed bed corresponding to near equilibrium scour conditions, and the results were compared to a similar high curvature 193° bend numerical study. Inner bank vortices and shear layers were present in both cases although their characteristics were substantially different. Distributions of boundary friction velocities, and turbulence were also quite different for each case.

La presente tesis tiene como objetivo evaluar una propuesta para el control de erosión fluvial de la curva externa del rio Rimác ubicada entre los sectores Cantagallo y La Perla en Chosica, verificando su eficacia a través de un modelamiento con fines de calcular la socavación producida para diferentes periodos de retorno y proponer como estructura de control a las paletas sumergidas, comparando ambos resultados obtenidos para evaluar sus beneficios. El tramo escogido presentó fallas en los muros de contención ubicados a lo largo del cauce según un estudio previo realizado por el INGEMMET, por lo que es necesario mejorar la infraestructura ya construida, por lo que la presencia de las paletas sumergidas podría actuar como tal. Por este motivo, el modelamiento hidráulico, realizado en el software Iber, nos permitirá conocer el comportamiento del río para obtener las variables de diseño y conocer los valores de velocidades y esfuerzos cortantes de fondo producidos en la curva externa. Se realizó la simulación para dos escenarios, uno considerando las máximas avenidas producidas en años previos y el segundo despreciando dichos valores. Esto nos permite comparar las dimensiones y comportamiento de ambas estructuras para un futuro diseño. Finalmente, en ambos escenarios se verificó que la presencia de las paletas sumergidas en la curva externa reduce los niveles de erosión local y general producido para los diferentes caudales simulados, por lo que resulta una estructura viable a ser aplicada como medida de control. / The objective of this thesis is to evaluate a proposal for the control of fluvial erosion of the external bend of the Rimac river located between the Cantagallo and La Perla sectors in Chosica, verifying its effectiveness through a modeling in order to calculate the undercut produced for different return periods and propose submerged vanes as a control structure, comparing both results obtained to evaluate their benefits. The chosen section presented failures in the retaining walls located along the channel according to a previous study carried out by INGEMMET, so it is necessary to improve the infrastructure already built, so the presence of the submerged vanes could act as such. For this reason, the hydraulic modeling, carried out in the Iber software, will allow us to know the behavior of the river to obtain the design variables and to know the values of speeds and shear stresses produced in the external bend. The simulation was performed for two scenarios, one considering the maximum avenues produced in previous years and the second disregarding these values. This allows us to compare the dimensions and behavior of both structures for a future design. Finally, in both scenarios it was verified that the presence of the submerged vanes in the external curve reduces the levels of local and general scour produced for the different simulated flows, making it a viable structure to be applied as a control measure. / Tesis